Effects of formalin fixation and prolonged block storage on detection of hepatitis C virus RNA in liver tissue.
It has been suggested that prolonged formalin fixation and block storage adversely affect hepatitis C virus (HCV) ribonucleic acid (RNA) detection in tissue by reverse transcriptase-polymerase chain reaction (RT-PCR). We attempted to determine whether short-term perfusion fixation (3-5 days) or prolonged formalin storage adversely affects the detection of HCV RNA in paraffin-embedded tissue in comparison with 24-h fixation. Also, we examined the effects of prolonged storage of paraffin blocks on the sensitivity for HCV detection. We performed RT-PCR in formalin-fixed explanted livers from 20 liver allograft recipients known to be HCV positive (10 with specimens stored for 2-4 years and 10 with specimens stored for > 4 years). We compared the results of perioperative needle liver biopsy specimens fixed overnight with liver sections fixed by perfusion for 3-5 days and bulk liver tissue stored in formalin for years (mean, 6.25 years; range, 2-11 years). HCV RNA was detected in 100%, 85%, and 0% of specimens fixed for 24 h, 3-4 days, and years, respectively. We conclude that HCV can be readily detected in tissue fixed by formalin overnight, sensitivity decreases slightly with intermediate-length fixation, and HCV is rendered undetectable by prolonged fixation. In addition, retention of formalin-fixed tissue in paraffin blocks does not affect the sensitivity of HCV detection.
Guerrero
R B
RB
Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA.
Batts
K P
KP
Brandhagen
D J
DJ
Germer
J J
JJ
Perez
R G
RG
Persing
D H
DH
D005557:Formaldehyde / Q000009:adverse effects; D016174:Hepacivirus / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008099:Liver / Q000737:chemistry / Q000821:virology*; D016133:Polymerase Chain Reaction / Q000379:methods; D014176:Protein Biosynthesis; D012367:RNA, Viral / Q000032:analysis*; D012680:Sensitivity and Specificity; D013997:Time Factors; D016707:Tissue Fixation / Q000379:methods*
D012367:RNA, Viral; D005557:Formaldehyde